Investigation on the degradation path of SF6 in a packed-bed plasma: Effect of plasma-generated radicals

SF 6 degradation mechanism in non-thermal plasma (NTP) systems is not fully understood due to the formation of a complex physico-chemical reaction network, especially when reactive gases and packing materials are involved. In this work, we conducted a combined experimental and theoretical study to unravel the SF 6 degradation path in a γ-Al 2 O 3 packed plasma in the presence of H 2 O or O 2 . Our experimental results show that both the H 2 O and O 2 have the synergetic effect with γ-Al 2 O 3 packing on promoting SF 6 degradation, leading to a high stable gas yields than typical spark or corona discharges. The H 2 O or O 2 addition promotes the SO 2 or SO 2 F 2 selectivity, respectively. Density functional theory (DFT) calculations reveal that the SO 2 generation corresponding with the highest activation barrier is the most critical step towards SF 6 degradation. Radicals like H and O generated from H 2 O or O 2 discharge can significantly promote the degradation process via Eley-Rideal mechanism, affecting the key reactions of stable products generation, advancing the degradation efficiency. The results of this work could provide insights on further understanding of SF 6 degradation mechanism specially in packed bed plasma systems.